Kerry in a March 9 statement called on the government of Iran to “work cooperatively with us on the investigation into his disappearance so we can ensure his safe return.” The statement said Levinson, if a captive, is one of the longest-held American citizens in history.

Levinson was on a private business trip when he disappeared, Kerry said, though the Washington Post reported in December that he had been working for the CIA in a rogue operation. Levinson, the father of seven children, is a private detective and former FBI agent.

Iran’s Foreign Minister Javad Zarif said in December that Levinson is not incarcerated in Iran under government auspices.

The FBI has announced a $1 million reward for any information leading to Levinson’s safe return. — jta